Fabrication of gold and silver hierarchically micro/nanostructured arrays by localized electrocrystallization for application as SERS substrates

Abstract

A simple and universal method, based on a polypyrrole (PPy) through-pore template induced by the colloidal monolayer, is developed to fabricate the gold and silver hierarchically micro/nanostructured arrays with a hexagonally packed pattern and controllable morphologies through electrochemical deposition. Using the polystyrene colloidal monolayer as the first template, a hexagonally packed PPy through-pore thin film was electrodeposited and used as a secondary template to adjust the interface electroconductivity, further to control the localized electrocrystallization process. Final electrodeposition under appropriate conditions can easily lead to several kinds of metal periodic arrays. These hierarchically micro/nanostructured arrays can be used as surface-enhanced Raman scattering (SERS) active substrates. Before use, a certain thickness of the gold layer was ion-sputtered onto the periodic arrays to eliminate the interference from PPy film and enhance the substrate SERS activity. Such a gold-covering strategy can also provide an effective method to clean the impurity-adsorbed SERS substrate, which is quite important in SERS-based applications.